Looks like a project.
When I soldered my panel pieces back togeather I turned down my soldering heat Temperature. What I wished I had was some silver solder. Something that would melt at a lower temp. I noticed that the panel material has a real low melting point, so be careful.
My spongy stuff was in bad shape too. I couldn't find anything to replace it with. What were you going to use to replace the sponge with?
Good luck
Buzz
